Termite mounds harness diurnal temperature oscillations for ventilation
Many species of millimetric fungus-harvesting termites collectively build uninhabited, massive mound structures enclosing a network of broad tunnels that protrude from the ground meters above their subterranean nests. It is widely accepted that the purpose of these mounds is to give the colony a con...
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| Other Authors: | |
| Format: | Article |
| Language: | en_US |
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National Academy of Sciences (U.S.)
2016
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| Online Access: | http://hdl.handle.net/1721.1/102259 https://orcid.org/0000-0002-1069-008X |
| _version_ | 1826198398645043200 |
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| author | King, Hunter Ocko, Samuel Alan Mahadevan, L. |
| author2 | Massachusetts Institute of Technology. Department of Physics |
| author_facet | Massachusetts Institute of Technology. Department of Physics King, Hunter Ocko, Samuel Alan Mahadevan, L. |
| author_sort | King, Hunter |
| collection | MIT |
| description | Many species of millimetric fungus-harvesting termites collectively build uninhabited, massive mound structures enclosing a network of broad tunnels that protrude from the ground meters above their subterranean nests. It is widely accepted that the purpose of these mounds is to give the colony a controlled microclimate in which to raise fungus and brood by managing heat, humidity, and respiratory gas exchange. Although different hypotheses such as steady and fluctuating external wind and internal metabolic heating have been proposed for ventilating the mound, the absence of direct in situ measurement of internal air flows has precluded a definitive mechanism for this critical physiological function. By measuring diurnal variations in flow through the surface conduits of the mounds of the species Odontotermes obesus, we show that a simple combination of geometry, heterogeneous thermal mass, and porosity allows the mounds to use diurnal ambient temperature oscillations for ventilation. In particular, the thin outer flutelike conduits heat up rapidly during the day relative to the deeper chimneys, pushing air up the flutes and down the chimney in a closed convection cell, with the converse situation at night. These cyclic flows in the mound flush out CO[subscript 2] from the nest and ventilate the colony, in an unusual example of deriving useful work from thermal oscillations. |
| first_indexed | 2024-09-23T11:04:15Z |
| format | Article |
| id | mit-1721.1/102259 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T11:04:15Z |
| publishDate | 2016 |
| publisher | National Academy of Sciences (U.S.) |
| record_format | dspace |
| spelling | mit-1721.1/1022592022-10-01T00:59:50Z Termite mounds harness diurnal temperature oscillations for ventilation King, Hunter Ocko, Samuel Alan Mahadevan, L. Massachusetts Institute of Technology. Department of Physics Ocko, Samuel Alan Many species of millimetric fungus-harvesting termites collectively build uninhabited, massive mound structures enclosing a network of broad tunnels that protrude from the ground meters above their subterranean nests. It is widely accepted that the purpose of these mounds is to give the colony a controlled microclimate in which to raise fungus and brood by managing heat, humidity, and respiratory gas exchange. Although different hypotheses such as steady and fluctuating external wind and internal metabolic heating have been proposed for ventilating the mound, the absence of direct in situ measurement of internal air flows has precluded a definitive mechanism for this critical physiological function. By measuring diurnal variations in flow through the surface conduits of the mounds of the species Odontotermes obesus, we show that a simple combination of geometry, heterogeneous thermal mass, and porosity allows the mounds to use diurnal ambient temperature oscillations for ventilation. In particular, the thin outer flutelike conduits heat up rapidly during the day relative to the deeper chimneys, pushing air up the flutes and down the chimney in a closed convection cell, with the converse situation at night. These cyclic flows in the mound flush out CO[subscript 2] from the nest and ventilate the colony, in an unusual example of deriving useful work from thermal oscillations. Human Frontier Science Program (Strasbourg, France) Massachusetts Institute of Technology. Department of Physics (Henry W. Kendall Physics Fellowship) 2016-04-19T16:29:44Z 2016-04-19T16:29:44Z 2015-09 2014-12 Article http://purl.org/eprint/type/JournalArticle 0027-8424 1091-6490 http://hdl.handle.net/1721.1/102259 King, Hunter, Samuel Ocko, and L. Mahadevan. “Termite Mounds Harness Diurnal Temperature Oscillations for Ventilation.” Proc Natl Acad Sci USA 112, no. 37 (August 27, 2015): 11589–11593. https://orcid.org/0000-0002-1069-008X en_US http://dx.doi.org/10.1073/pnas.1423242112 Proceedings of the National Academy of Sciences Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf National Academy of Sciences (U.S.) National Academy of Sciences (U.S.) |
| spellingShingle | King, Hunter Ocko, Samuel Alan Mahadevan, L. Termite mounds harness diurnal temperature oscillations for ventilation |
| title | Termite mounds harness diurnal temperature oscillations for ventilation |
| title_full | Termite mounds harness diurnal temperature oscillations for ventilation |
| title_fullStr | Termite mounds harness diurnal temperature oscillations for ventilation |
| title_full_unstemmed | Termite mounds harness diurnal temperature oscillations for ventilation |
| title_short | Termite mounds harness diurnal temperature oscillations for ventilation |
| title_sort | termite mounds harness diurnal temperature oscillations for ventilation |
| url | http://hdl.handle.net/1721.1/102259 https://orcid.org/0000-0002-1069-008X |
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